Electronic Flora of South Australia Genus Fact Sheet

Genus DISTROMIUM Levring 1940: 3, figs 2,3

Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae

Thallus flabellate, entire or lacerate, or multifid with narrow branches from the base, with a rhizoidal holdfast. Growth by a row of apical cells, with the thallus becoming 2 cells thick immediately below the apical cells and remaining distromatic throughout. Phaeoplasts numerous per cell, discoid. Hairs present or absent, in concentric zones or scattered tufts.

Reproduction: Unilocular sporangia in indusiate sori, forming concentric lines or patches, external to the blades, producing four spores. Sexual plants unknown apart from antheridia on sporangial plants of D. multifidum.

Life history unknown, possibly direct from the sporophyte.

Type species: D. skottsbergii Levring.

Taxonomic notes: A genus of some 5 species, from Juan Fernandez I., southern Australia, Lord Howe I. and Japan, differing from Chlandidophora in habit (without laterals which become inactive) and in having the sporangia in indusiate sori rather than scattered.

References:

LEVRING, T. (1940). Die Phaeophyceengattungen Chlanidophora, Distromium und Svringoderma. K. fysiogr. sällsk. Lund. Forh. 10(20), 1–11.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

KEY TO SPECIES OF DISTROMIUM

1. Thallus flabellate, entire or split, with segments 5–20 (–35) mm broad near their apices

I. D. flabellatum

1. Thallus multifid, with narrow, elongate branches 2–4 mm broad

D. multifidum


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